package com.hmdp.service.impl;

import cn.hutool.core.bean.BeanUtil;
import com.hmdp.dto.Result;
import com.hmdp.entity.VoucherOrder;
import com.hmdp.mapper.VoucherOrderMapper;
import com.hmdp.service.ISeckillVoucherService;
import com.hmdp.service.IVoucherOrderService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import com.hmdp.utils.RedisIdWorker;
import com.hmdp.utils.UserHolder;
import io.lettuce.core.XReadArgs;
import org.redisson.api.RLock;
import org.redisson.api.RedissonClient;
import org.springframework.aop.framework.AopContext;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.connection.stream.*;
import org.springframework.data.redis.core.StringRedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

import javax.annotation.PostConstruct;
import javax.annotation.Resource;
import java.time.Duration;
import java.util.Collections;
import java.util.List;
import java.util.Map;
import java.util.concurrent.ArrayBlockingQueue;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.ExecutorService;
import java.util.concurrent.Executors;

/**
 * <p>
 *  服务实现类
 * </p>
 *
 */
@Service
public class VoucherOrderServiceImpl extends ServiceImpl<VoucherOrderMapper, VoucherOrder> implements IVoucherOrderService {
    @Resource
    private ISeckillVoucherService seckillVoucherService;
    @Autowired
    private RedisIdWorker redisIdWorker;
    @Autowired
    private StringRedisTemplate stringRedisTemplate;
//    基于redistemplate的开源框架 实现了分布式相关的工具集合 比如分布式锁
    @Resource
    private RedissonClient redissonClient;
    private static final DefaultRedisScript<Long> SECKILL_SCRIPT;
    static {
        SECKILL_SCRIPT = new DefaultRedisScript<>();
        SECKILL_SCRIPT.setLocation(new ClassPathResource("seckill.lua"));
        SECKILL_SCRIPT.setResultType(Long.class);
    }
//    阻塞队列 存放待创建的订单
//    private BlockingQueue<VoucherOrder> orderTasks = new ArrayBlockingQueue<>(1024*1024);
//    单线程异步处理任务
    private static final ExecutorService SECKILL_ORDER_EXECUTOR = Executors.newSingleThreadExecutor();
    // 在类初始化的时候执行
    @PostConstruct
    private void init(){
        SECKILL_ORDER_EXECUTOR.submit(new VoucherOrderHandeler());
    }

    @Override
    public Result seckillVoucher(Long voucherId) {
        //      1.  执行lua脚本 判断购买资格
        Long userId = UserHolder.getUser().getId();
        long orderId= redisIdWorker.nextId("order");
        Long result = stringRedisTemplate.execute(
                SECKILL_SCRIPT,
                Collections.emptyList(),
                voucherId.toString(), userId.toString(),String.valueOf(orderId));
        //      2.  不为0 没有购买资格
        int r = result.intValue();
        if(r!=0){
            return Result.fail(r == 1?"库存不足":"重复下单");
        }
        //        5.获取代理对象
        proxy = (IVoucherOrderService)AopContext.currentProxy();
        return Result.ok(orderId);
    }



    //    线程任务
    private class VoucherOrderHandeler implements Runnable {
        String queueName = "streams.orders";

        @Override
        public void run() {
            while (true) {
                try {
                    //1.获取订单消息 XREADGROUP GROUP g1 c1 BLOCK 2000 STREAMS streams.order >
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1).block(Duration.ofSeconds(2)),
                            StreamOffset.create(queueName, ReadOffset.lastConsumed())
                    );
                    //2.判断消息获取是否成功
                    if (list == null || list.isEmpty()) {
                        //2.1未成功 继续下一次循环
                        continue;
                    }
                    //若成功 可以下单
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> values = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(values, new VoucherOrder(), true);
                    //创建订单
                    handleVoucherOrder(voucherOrder);
                    //ACK确认 SACK streams.orders g1 id
                    stringRedisTemplate.opsForStream().acknowledge(queueName, "g1", record.getId());
                } catch (Exception e) {
                    log.error("处理订单异常", e);

                }
            }
        }

        private void handlePendingList() {
            while (true) {
                try {
                    //1.获取未确认订单消息 XREADGROUP GROUP g1 c1  STREAMS streams.order 0
                    List<MapRecord<String, Object, Object>> list = stringRedisTemplate.opsForStream().read(
                            Consumer.from("g1", "c1"),
                            StreamReadOptions.empty().count(1),
                            StreamOffset.create(queueName, ReadOffset.from("0"))
                    );
                    //2.判断消息是否为空
                    if (list == null || list.isEmpty()) {
                        //2.1为空 结束
                        break;
                    }
                    //若成功 可以下单
                    MapRecord<String, Object, Object> record = list.get(0);
                    Map<Object, Object> values = record.getValue();
                    VoucherOrder voucherOrder = BeanUtil.fillBeanWithMap(values, new VoucherOrder(), true);
                    //创建订单
                    handleVoucherOrder(voucherOrder);
                    //ACK确认 SACK streams.orders g1 id
                    stringRedisTemplate.opsForStream().acknowledge(queueName, "g1", record.getId());
                } catch (Exception e) {
                    log.error("处理订单异常", e);
                    //抛出异常后会继续下一次循环
                }
            }
        }
    }

    private IVoucherOrderService proxy;

    private void handleVoucherOrder(VoucherOrder voucherOrder){
//        获取用户
        Long userId = voucherOrder.getUserId();
        Long voucherId = voucherOrder.getVoucherId();
        RLock lock = redissonClient.getLock("lock:order:" + userId);
//        获取锁
        boolean isLock = lock.tryLock();
//        判断是否获取锁成功
        if(!isLock){
//            失败
            log.error("不允许重复下单");
        }
        try {
//          注意：事务是由AOP代理对象实现的 内部调用只能调用业务方法 无法使事务生效
//          因此要获取当前类的代理对象 再调用
            proxy.createVoucherOrder(voucherOrder);
        }finally {
            lock.unlock();
        }
    }
    @Transactional
    @Override
    /**
     * 创建优惠券订单
     */
    public void createVoucherOrder(VoucherOrder voucherOrder){

            Long userId = voucherOrder.getUserId();
//            一人一单
            int count = query()
                    .eq("voucher_id",voucherOrder.getVoucherId())
                    .eq("user_id",userId)
                    .count();
            if(count>0){
                log.error("不允许重复下单");
                return;
            }
//         扣减库存
            boolean success = seckillVoucherService.update()
                    .setSql("stock = stock - 1")
                    .eq("voucher_id", voucherOrder.getVoucherId()).gt("stock", 0)//where id = ? and stock = ?
                    .update();
            if (!success) {
//            扣减失败 兜底 缓存层面其实已经判断过了
                log.error("库存不足");
                return;
            }
//            保存订单
            save(voucherOrder);
    }
//    基于redis的stream实现消息队列

//    JVM中用阻塞队列来实现消息队列
//    @Override
//    public Result seckillVoucher(Long voucherId) {
////      1.  执行lua脚本 判断购买资格
//        Long userId = UserHolder.getUser().getId();
//        Long result = stringRedisTemplate.execute(
//                SECKILL_SCRIPT,
//                Collections.emptyList(),
//                voucherId.toString(), userId.toString());
////      2.  不为0 没有购买资格
//        int r = result.intValue();
//        if(r!=0){
//            return Result.fail(r == 1?"库存不足":"重复下单");
//        }
////       3.  为0 有购买资格 下单信息保存到阻塞队列
//        long orderId= redisIdWorker.nextId("order");
//        VoucherOrder voucherOrder = new VoucherOrder();
//        voucherOrder.setId(orderId);
//        voucherOrder.setUserId(userId);
//        voucherOrder.setVoucherId(voucherId);
////        4.订单放入阻塞队列
//        orderTasks.add(voucherOrder);
////        5.获取代理对象
//        proxy = (IVoucherOrderService)AopContext.currentProxy();
//        return Result.ok(orderId);
//    }
    /**
     * 秒杀下单
     * @param voucherId
     * @return
     */
//    @Override
//    public Result seckillVoucher(Long voucherId) {
////        1.查询优惠券
//        SeckillVoucher voucher = seckillVoucherService.getById(voucherId);
////        2.判断秒杀是否开始
//        if(voucher.getBeginTime().isAfter(LocalDateTime.now())){
//            return Result.fail("秒杀尚未开始！");
//        }
////        3.判断秒杀是否结束
//        if(voucher.getEndTime().isBefore(LocalDateTime.now())){
//            return Result.fail("秒杀已结束！");
//        }
////        4.判断库存是否充足
//        if(voucher.getStock()<1){
//            return Result.fail("库存不足！");
//        }
////        一人一单
//        Long userId = UserHolder.getUser().getId();
////        此方法只适用于单体 不适用于集群或分布式
////        toString返回的是对象 不同线程统一用户id产生的不同的String对象
////        synchronized (userId.toString().intern()){
//////            注意：事务是由AOP代理对象实现的 内部调用只能调用业务方法 无法使事务生效
//////            因此要获取当前类的代理对象 再调用
////            IVoucherOrderService proxy = (IVoucherOrderService)AopContext.currentProxy();
////            return proxy.createVoucherOrder(voucherId);
////        }
////        创建锁对象 自定义的基于redistamplate
////        SimpleRedisLock lock = new SimpleRedisLock("order:" + userId, stringRedisTemplate);
//        RLock lock = redissonClient.getLock("lock:order:" + userId);
////        获取锁
//        boolean isLock = lock.tryLock();
////        判断是否获取锁成功
//        if(!isLock){
////            失败
//            return Result.fail("不允许重复下单");
//        }
//        try {
////          注意：事务是由AOP代理对象实现的 内部调用只能调用业务方法 无法使事务生效
////          因此要获取当前类的代理对象 再调用
//            IVoucherOrderService proxy = (IVoucherOrderService)AopContext.currentProxy();
//            return proxy.createVoucherOrder(voucherId);
//        }finally {
//            lock.unlock();
//        }
//    }
}
